www.jec.org.uk

Hi guys,

I had to replace my washer bottle pump as the old one nearly caused an MOT failure. SNG Barratt have duly supplied a replacement which is an up to date version, with similar electrical connection, however, it won't pump any water out. I don't think there's anything wrong with the pump as it's the second one I've had, hence the puzzle.
As you should be able to see, the terminals on the pump are + on the right and - on the left. However the plug on the loom is green/black on the left and black on the right.......in a plug that can't be connected wrongly as there is an overlapping part to cover the terminals. To my mind, black has to be negative, and therefore green/black, positive. But the old pump has the same configuration and used to work (weakly).

So what to do?, force the spade connectors out of the loom plug and try them the other way round, or am I missing something so obvious that I'm going to make myself look really stupid?!.....I'll risk it!

Cheers, Simon.

Hi Simon - so I guess you're wondering if the polarity of the new pump is the same as your car?
I would put a meter across the loom side of the plug to see what the car is supplying ie which connector is live and which the ground?
Then I'd use a power probe to check the polarity of the pump by running it either way to see which way round it pumps.
Then you'll be able to see if the pump is being run the wrong way round.
Hope that helps

Hi David,

Thanks for your advice, the polarity was indeed reversed but not having ownership of a power probe I took a more basic approach and made up some short wires with the appropriate spade connectors, thereby swapping the connections from the plug and squirt it went....

I still don't understand why as if you look at this, the + and - on the pump are the same old and new:
However, it works so all's well etc. The new pump is much more efficient to the tune that the pipes leaked at the "T" piece so that had to be sorted too, and all for the MOT technician to check it once a year!!

Off to research power probes now, though of course I hope I never have to use it!

Cheers, Simon.

Hi Simon - it sounds like your mystery is solved. As you've had 2 the same are SNGB manufacturing them the wrong way round do you think? It might be worth giving them some feedback on that.
A power probe is a very handy tool for investigating electrical issues. Mine is only a basic one that cost about £20 and it allows me to power up a component like your washer pump and other things like testing for a live circuit or continuity. Well worth adding to your tool box!